Paperboard envelopes or containers, with interlocking tongue and slot features, for containing and mailing or transporting material are well known. U.S. Pat. No. 4,765,485 (to Perkins) discloses a paperboard mailing envelope having such an interlocking tongue and slot formed on the closure flap and on the back panel. The tongue and slot are adapted to interlock to prevent undetected opening. The Perkins envelope further discloses a tear strip to provide for opening the envelope. Although suitable for mailing or transporting items, the envelope disclosed by Perkins is not designed to be convertible to provide a means for displaying the items formerly contained therein after it has been opened.
U.S. Pat. No. 4,343,105 (to Isaacson) discloses a display device including an ordinary mailing envelope with a slot in the back. A stiff fibre-board card is inserted in the envelope, and includes a tab or tongue which is pushed outwardly through a slot in the back of the envelope to serve as a prop to support the envelope in a manner of a display card for counters or shelves in stores. While the Isaacson display device provides a stand for pictures, it may be difficult to manipulate the stiff planar member through the slot in the envelope, and the corners of the slot may tend to tear under the pressure imposed by the support member. Further, no provision is made for mounting or attaching material on the outside surface of the device.
U.S. Pat. No. 3,656,613 (to LaFrance et al.) discloses a folder for stranded material, such as tinsel or other strands. The folder has two main panels foldably connected, and side panels connected to each main panel to form pouches to hold the strands in position. The main panels may be folded upon themselves and sealed by a glue patch. For opening the folder, a tear strip is provided and a viewing window may be provided in one of the main panels so that the contents of the folder may be viewed without opening; however, in the viewing mode, the panels are spaced from one another at their free ends and not connected, and, therefore, do not provide the stability required for secure display of a picture or the like.
U.S. Pat. Nos. 1,515,901 (to Helmquest), 1,539,619 (to Wood), 2,310,371 (to Lines et al.), and 4,014,434 (to Thyen) respectively disclose a mount for displaying photographs, a somewhat similar mount, an envelope for containing photographic material with a tear strip opening feature, and a folder provided with means for locking the folder panels in the folder configuration. None of these four patents discloses or suggests a convertibility feature.
U.S. Pat. No. 4,780,975 (to Friedman) discloses a combined mailer and easel-type display frame for a blank. The Friedman mailer with easel requires three panels, one of which includes a brace panel with a tongue portion for engaging a slot in the lower panel to create a support easel. The brace panel is defined by multiple parallel sections with fold lines therebetween, but there is no disclosure of how to incorporate a tear strip opening feature for the mailer. Somewhat similarly, U.S. Pat. No. 2,845,733 (to Fox) discloses a combination envelope and easel for containing and/or framing pictures or the like. The Fox envelope and easel requires adhesive or gum connections between the flaps, which are manipulated to form the support portions for the easel. It does not disclose a tear strip to facilitate the opening of the envelope.
Accordingly, there is a need for a convertible mailing envelope for containing materials such as photographic prints, wherein the envelope may be opened easily and converted easily to provide an easel on which photographic prints or the like may be displayed for viewing.